1. Field of the Invention
The present invention relates to an electro-luminescence display device, and more particularly, to a method and apparatus for driving an electro-luminescence display panel capable of doing an aging operation upon driving.
2. Description of the Related Art
In recently, there has been developed various flat panel displays with a reduced weight and bulk that are free from the disadvantage of a cathode ray tube CRT. Such flat panel displays include a liquid crystal display LCD, a field emission display FED, a plasma display panel PDP, and an electro-luminescence (hereinafter, referred to as an EL) display devices.
Among these, the EL display panel is a self-luminous device capable of light-emitting a phosphorous material by a re-combination of electrons with holes. The EL display panel is generally classified into an inorganic EL panel using the phosphorous material as an inorganic compound and an organic EL panel using it as an organic compound. Such an EL display panel has many advantages of a low voltage driving, a self-luminescence, a thin-thickness, a wide viewing angle, a fast response speed and a high contrast, etc, such that it can be highlighted into a post-generation display device.
The EL display device includes: an anode formed of a transparent conductive material on a substrate; and a hole injection layer, a hole carrier layer, a light-emitting layer, an electron carrier layer, and an electron injection layer made of an organic material, and a cathode made of a metal having a low work function, which are disposed thereon. If a forward voltage is applied between the anode and the cathode, then electrons generated from the cathode move via the electron injection layer and the electron carrier layer to the light-emitting layer and holes generated from the anode moves via the hole injection layer and the hole carrier layer to the light-emitting layer. Accordingly, the electrons and the holes fed from the electron carrier and the hole carrier layer are recombined each other in the light-emitting layer, to thereby emit light. In this case, the brightness of the organic EL device is in portion to a current between the anode and the cathode.
FIG. 1 is a circuit diagram showing equivalently a passive matrix type organic EL display device in which an organic EL element is arranged in a matrix type, and FIG. 2 is a driving waveform diagram of an EL panel 20 shown in FIG. 1.
The EL display device shown in FIG. 1 includes: an EL panel 20 having an EL cell 26 formed at a cross of both scan lines SL1 to SLn and data lines DL1 to DLm; a scan driver 22 for driving the scan lines SL1 to SLn; and a data driver 24 for driving the data lines DL1 to DLm.
Each of the EL cells 26 formed in the EL panel 20 is represented as a diode, which is connected in a forward direction between the data line DL and the scan line SL. Herein, the data line DL is equivalently an anode and the scan line SL is equivalently a cathode. If a negative scan pulse, that is, a low scan voltage Vlow, is supplied to the scan line SL and a positive data signal(current) is supplied to the data line DL to as shown in FIG. 2 apply a forward voltage to each EL cell 26, then each EL cell 26 emits light to generate light corresponding to the data signal. On the other hand, if a high scan voltage Vhigh is supplied to the scan line SL to thereby apply a reverse voltage to each EL cell 26, then each EL cell 26 does not emit light.
The scan driver 22, as shown in FIG. 2, sequentially supplies a scan pulse to a n number of scan lines SL1 to SLn. In other words, the scan driver 22 sequentially supplies the low scan voltage Vlow to the scan lines SL1 to SLn during a scan period to thereby sequentially make the scan lines SL1 to SLn to be enable, and supplies the high scan voltage Vhigh during the rest period to make the scan lines SL1 to SLn to be disable. Further, the scan driver 22 repeats the sequential driving of the scan lines SL1 to SLn for each frame F.
The data driver 24 supplies the data signal to the m number of data lines DL1 to DLm for each period when the scan lines SL1 to SLn are enabled.
In order for a stable driving in the related art organic EL display device, an aging process to make the EL cells 26 to be a reverse bias state is performed in manufacturing process. However, even the aging process is performed in the organic EL display device during the manufacturing process, the organic EL display device has a problem that its life-span becomes shorten because the EL cells 26 becomes deteriorated with the passage of driving time or a line defect such as short defect becomes generated due to a stress. In order to solve this problem, an aging operation is needed in the driving of the organic EL display device.